WASHINGTON — The Senate is poised to rewrite the federal government’s principal anti-domestic abuse law with new protections for gays, lesbians, immigrants and Native American women.

A vote to reauthorize the 1994 Violence Against Women Act, expected to come late Thursday or Friday, sets up a possible showdown with the House, which last year rejected the Senate’s more ambitious approach.

The Violence Against Women Act, or VAWA, is credited with helping significantly reduce incidents of domestic violence over the past two decades. But the law expired in 2011 and Congress has since struggled to come up with a replacement version that would both extend the act and expand its reach. Last year, both chambers passed bills but the congressional session ended before differences could be resolved.

Democrats pounced on the failure to renew the law during the election campaign last fall, characterizing Republicans as unfriendly on women’s issues. In the wake of the elections, Republicans this year have seemed eager to get a bill passed quickly.

The bill, expected to easily pass the Senate, is largely the same as last year’s measure. It specifies that underserved communities, including those defined by sexual orientation and gender identity, should receive equal treatment under the act and it also improves protections for immigrant women subject to abusive or violent marriages.

It strengthens the ability of tribal communities to prosecute non-Indians who assault Indian partners on tribal lands. Indian women are victims of domestic abuse at far higher rates than the national average, but their attackers often go unpunished because federal prosecutors don’t have the resources to pursue misdemeanor crimes on isolated reservations.

While some House Republicans last year questioned the Senate’s need to single out gays and lesbians as eligible for this protection, the main issue last year and again this year was that of tribal authority to try non-Indians.

Republicans said the Senate provision was unconstitutional, citing a 1978 Supreme Court decision which held that in most cases tribes did not have the authority to try non-Indians. Senate sponsors said their bill would be upheld by the courts.

The bill, said Sen. Patrick Leahy, D-Vt., chairman of the Senate Judiciary Committee, “will allow us to make real progress in addressing the horrifying epidemic of domestic violence in tribal communities.”

Leahy cited a recent study finding that almost three-fifths of Native American women have been assaulted by their spouses or intimate partners.

House Majority Leader Eric Cantor, R-Va., the lead player in crafting the House bill, said Wednesday he had been having daily meetings on how best to move the bill forward, and had been in touch with the office of Vice President Joe Biden, who as a senator was a lead sponsor of the original 1994 bill.

Speaking on the House floor, Cantor said that “while we want to protect the women who are subject to abuse on tribal lands,” the bill had been “complicated” by other issues. “I hope to be able to deal with this, bring it up in an expeditious manner.”

A possible solution has been offered by Republican Reps. Tom Cole of Oklahoma, one of three House members of Indian heritage, and Darrell Issa, R-Calif. They have proposed giving non-Indians the right to request that their case be moved to a federal court if they feel they are not receiving a fair trial.

Cole, in an interview, said he was meeting with Cantor and others involved on the issue and there was a “genuine effort to find common ground.” He 1 in 3 Native American women are subject to sexual assault in their lifetimes, often by non-Indians, and that federal authorities often are too far away to help. Cole called it “bizarre” that tribal leaders were unable to pursue cases.

Under the existing law, the federal government provides grants to states and local governments for services such as transitional housing, legal assistance and law enforcement training. This has helped increase rates of prosecution and conviction of offenders by helping communities develop dedicated law enforcement units for domestic violence. VAWA’s National Domestic Violence Hotline receives more than 22,000 calls a month. The law also established the Office on Violence Against Women within the Justice Department.

The Senate bill would authorize $659 million over five years for the programs, down 17 percent from the last reauthorization in 2005. The bill also gives more emphasis to sexual assault prevention and takes steps to reduce the rape kit backlog.

It removes a provision that Republicans objected to last year that would have increased visas for immigrant victims of domestic violence.